NORTH AMERICAN COLEOPTERA. 23 



Platypsylla castoris Kits. 



Form elongate-oval, equally narrowed at either extremity, about 

 three times as long as wide, depressed. Color whitish. Length 1.6 

 mm. PL iii, figs. 17-18. 



Head semicircular, more obtuse in front, hind angles distinct, a 

 long seta directed outAvardly arising from near the hind angles, be- 

 neath Avith six shorter setje directed backward arising near the pos- 

 terior border. Eyes wanting. PI. iii, fig. 19. 



Antennae four-jointed, arising under the hind angles of the head. 

 First joint short and broad, second narrower, bearing a spiniform 

 process at the front angle ; third cylindrical, narrower ; fourth very 

 narrow, bearing two setse at its end. The joints are capable of tele- 

 scopic retraction. PI. iii, fig. 20. 



Mentum quadrate, a little longer than wide, supported l)y a short 

 peduncle of the gula ; ligula not distinctly separated, but broader 

 than the mentum, emarginate in front, the angles rounded. Labial 

 palpi short, two-jointed, inserted at the side of mentum at the prob- 

 able point of separation in the ligula. 



Maxill.e flattened, pyriform, rapidly narrowing at apical third, 

 terminating in a narrow, obtuse process. Maxillary palpi short, 

 three-jointed, arising at the sides of the maxillte a little more than 

 one-third from the apex. PI. iii, fig. 19. 



Mandibles conical, but slender and flattened, semi-corneous, 

 arising from the sides of the buccal cavity exterior to, but a little in 

 front of the maxilhe, slightly overlapping the apices of the latter, 

 the tips of the mandibles crossing each other in front. 



Thoracic segments gradually wider, hind angles obtuse, upper 

 side with four long setse, the two near the hind angles directed out- 

 wardly and backward, those each side of middle directed backward, 

 the lateral margin bearing a short spine near the middle. Underside 

 of each thoracic segment with six or eight moderately long setae 

 arising near the posterior border and directed backwards. 



Abdominal segments nine. First narrower than either the meta- 

 thorax or the next, and without the short spine near the side margin. 

 Segments 2-7 similar in form, each with the short lateral spine, 

 eighth without lateral spine, ninth rapidly narrowed, the apex ob- 

 tuse. Dorsal side of segments bearing four setse as in the thoracic 

 segments ; ventral side with four pairs of long setse, between which 



